/*
 * ProGuard -- shrinking, optimization, obfuscation, and preverification of Java bytecode.
 *
 * Copyright (c) 2002-2018 GuardSquare NV
 *
 * This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later
 * version.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with this program; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
package proguard.obfuscate;

import proguard.classfile.Clazz;

/**
 * NameFactory which only generates names that don't exist yet as members on the class for which it is created.
 *
 * @author Johan Leys
 */
public class UniqueMemberNameFactory implements NameFactory {
    private static final String INJECTED_MEMBER_PREFIX = "$$";

    private final NameFactory delegateNameFactory;
    private final Clazz clazz;

    /**
     * Utility for creating a new NameFactory that can generate names for injected members: the generated names are
     * unique within the given class, and don't clash with non-injected members of its super classes.
     *
     * @param clazz the class for which to generate a NameFactory.
     * @return the new NameFactory instance.
     */
    public static UniqueMemberNameFactory newInjectedMemberNameFactory(Clazz clazz) {
        return new UniqueMemberNameFactory(new PrefixingNameFactory(new SimpleNameFactory(), INJECTED_MEMBER_PREFIX),
            clazz);
    }

    /**
     * Creates a new UniqueMemberNameFactory.
     * 
     * @param delegateNameFactory the delegate NameFactory, used for generating new candidate names.
     * @param clazz the class in which to check for existing member names.
     */
    public UniqueMemberNameFactory(NameFactory delegateNameFactory, Clazz clazz) {
        this.delegateNameFactory = delegateNameFactory;
        this.clazz = clazz;
    }

    // Implementations for NameFactory.

    public String nextName() {
        String name;

        // Check if the name doesn't exist yet. We don't have additional
        // descriptor information, so we can only search on the name.
        do {
            name = delegateNameFactory.nextName();
        } while (clazz.findField(name, null) != null || clazz.findMethod(name, null) != null);

        return name;
    }

    public void reset() {
        delegateNameFactory.reset();
    }
}